Unaudited Condensed Consolidated Balance Sheet (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Stockholders' Equity:
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	185,855,605	192,428,122
Common stock, shares outstanding	182,250,721	181,470,582